To prepare for that eventuality, the Obama campaign has, for the first time, really, begun to bank delegates. Sources close to the campaign estimate that as many as three dozen Democratic superdelegates have privately pledged to announce their support for Obama on June 4 or 5. The campaign is determined that Obama not end the first week in June without securing the support of delegates numbering 2026 — or 2210, as the case may be.

We had noted last week that Obama wasn’t all that many superdelegates away from a scenario where he could clinch on the night of the South Dakota and Montana primaries on June 3rd. Although the mathematics depend greatly on what happens with Michigan and Florida on Saturday, under the most likely scenario — that Florida and Michigan’s delegations are cut in half, and that Obama gets all of Michigan’s uncommitted delegates — he will in fact be about three dozen superdelegates away following next week’s primaries, exactly the number that Ambinder cites. (I presently show Obama’s magic number under this scenario at 31, accounting for his projected totals in Puerto Rico, South Dakota and Montana).

So why hold back on unfurling these endorsements until after South Dakota and Montana? Wouldn’t it look better to have the voters put you over the top?

Maybe — if your opponent weren’t someone as popular (and uncompromising) as Hillary Clinton. If these endorsements came in before all states had voted, Obama would risk looking as though he’d shoved Clinton aside. But that’s not really a problem after Montana and South Dakota are finished voting.

Moreover, holding back gives Clinton perhaps a 48-hour window to withdraw from the race on her own terms — particularly if she knows that the flood is coming. In this respect, I’d expect Obama’s avalanche of endorsers to become one of the worst-kept secrets in Washington, and to see more “leaks” to well-placed sources like Ambinder.

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